Tech Talk

ADX Follower Databases – Sharing Is Caring

ADX Follower Databases – Sharing Is Caring
  • Christoph Thale

  • 6 min

  • February 26, 2024

ADX Follower Databases let you share data from a lead cluster with independent teams – read-only, always in sync, no copying. Here's how to deploy and tear them down with Terraform.

Share ADX Data Across Teams Without Duplicating It

A follower database connects an ADX lead database to a separate follower cluster in read-only mode. The follower uses the same underlying Blob Storage – meaning data is synchronised within seconds to minutes.

Why Use a Follower Database?

Separate teams (e.g. data science) can run heavy analyses on the follower cluster without impacting production. Access is individually configurable; multiple teams can use it simultaneously.

Deploy With Terraform

Use the official azurerm provider to define the lead and follower clusters, then attach databases via an ARM template resource block. Key parameter:

  • defaultPrincipalsModificationKind: Replace (recommended) – the follower defines its own permissions independently

Apply with: terraform init / terraform plan / terraform apply

Tear It Down

Terraform can destroy the ARM template itself but not the resulting follower database resource in Azure. To remove the connection use a PowerShell script via Connect-AzAccount and Remove-AzKustoAttachedDatabaseConfiguration.